Apparatus for pumping liquids from containers



April 28, 1964 K. ZIMMERMANN APPARATUS FOR PUMPING LIQUIDS FROM CONTAINERS 2 Sheets-Sheet 1 Filed June 23, 1961 INVENTOR Karl Z/mmermann by fi/M ATTORNEYS" April 28, 1964 K. ZIMMERMANN 3,130,878

APPARATUS FOR PUMPING LIQUIDS FROM CONTAINERS 2 Sheets-Sheet 2 Filed June 23, 1961 INVENTOR ATTORNEYS United States Patent 3,130,87 8 APPARATUS FOR PUMPING LIQUIDS FROM CONTAINERS Karl Zimmermann, Muenchenstein, Switzerland, assignor to Ciba Limited, Basel, Switzerland, a company of Switzerland Filed June 23, 1961, Ser. No. 119,218 Claims priority, application Switzerland June 23, 1960 2 Claims. (Cl. 222318) In centrifugal pumps and similar rotary pumps, the interior of the pump housing has to be filled with the liquid to be pumped, so that the pump can exert a suction action. Thus, in order to ensure automatic suction of such pumps at all times, it is necessary that at least the rotor of the pump should remain immersed in the liquid to be delivered. Thus, if the pump is used for completely emptying containers, the pump must be arranged at the very bottom of the container, and with large containers this necessitates a very long connecting shaft between the submerged pump and the driving means generally an electric motor) disposed outside and above the container.

It has therefore been proposed to ensure the automatic suction of such pumps by arranging the pump so that it is immersed in liquid within a closed supplementary vessel. With this arrangement it is necessary, when the pump is turned off, to prevent the column of liquid running back into the container from the siphoning out of the supplementary vessel, because otherwise the pump will no longer be filled with liquid and automatic suction can no longer take place. To this end, a passage of narrow cross-section is generally provided to afford communication between the suction side and the pressure side of the pump, so that there is no substantial loss of delivery liquid during operation of the pump. When the pump is stopped, air can pass directly from the pressure line to the suction line, so that siphoning out of the supplementary vessel is avoided. Such a pump is described, for example in British Patent No. 864,620 to Ciba Limited, Basel, Switzerland. In this pump the suction pipe terminates close to the top cover of the supplementary vessel and the siphoning out is ensured through a small orifice in the pressure pipe, which also opens into the vessel. During operation, the liquid issuing from the suction pipe falls on to the surface of the liquid in the supplementary vessel and in so doing may entrain air bubbles. If this air enters the pump it may prevent the pump operating properly. Furthermore, with liquids having a low boiling point or a tendency to foam, a troublesome formation of foam and bubbles may occur, owing to the high location of the opening of the suction pipe.

The present invention provides an improved apparatus for pumping a liquid from a container, which comprises a vessel within which is enclosed a centrifugal pump the suction side of which communicates through an opening with the interior of the vessel, a pressure pipe which extends upwardly from the vessel and communicates with the pressure side of the pump, a suction pipe which extends downwardly for delivering liquid from a container to said vessel, and which suction pipe opens in the vessel near the bottom thereof and has an elbow bend above the level of the top of the vessel, and a narrow passage which aifords communication between the elbow bend of the suction pipe and the portion of the pressure pipe extending upwardly fiom the level of the said elbow bend.

An example of apparatus constructed in accordance with the invention is shown in the accompanying drawings, in which:

FIGURE 1 shows the arrangement of such a centrifugal pump for emptying a container, and

ice

FIGURE 2 shows the details of the pump in longitudinal section.

FIGURE 1 shows the arrangement of a centrifugal pump within a container 10. The pump is mounted on a fixing flange 12 which is screwed to the opening 14 of the container 10. Above the flange 12 is a motor 16, and the pump itself is disposed within a supplementary vessel 18, which, as shown, is disposed on the suction side of the pump. Into the supplementary vessel there extends a suction pipe 20 having an elbow bend and the suction opening 22 of which is located close to the bottom of the storage container 10. The pressure pipe 24 emerges from the upper end of the supplementary vessel 18 and is connected by means of a flange 26 to a pipe 28.

FIGURE 2 shows the supplementary vessel 18 in section. Within the vessel 18 the rotor 30 of the centrifugal pump is disposed within the pump housing 32. The driving shaft 34 is surrounded by a tube 36, which extends beyond the highest level of the liquid in the container 10. The upper end of the driving shaft 34 is journalled in a bearing 38 of the flange plate 12, and its lower end in a bearing 42. The bearing 42 is so arranged that it is always immersed in the liquid so as to prevent seizure, owing, for example, to crystallization. This could occur in a hearing which is allowed to dry when out of operation. If the length of the shaft 34 between the motor 16 and the rotor 30 is not too great, the bearing 42 may, if desired, be dispensed with. At the upper end of the tube 36 there is a seal 40, for example, a sliding ring packing or stuffing box, which is designed to prevent the escape of vapour, etc. from the vessel.

The suction pipe 20, which connects the supplementary vessel 18 with the liquid to be pumped from the container 10 has an elbow bend. It terminates with an opening 44 close to the bottom of the supplementary vessel 18. The suction pipe communicates at its highest point, namely at the elbow bend 48, with the pressure pipe 24 through a conduit 5%) of relatively narrow cross-section. The cross-section of the conduit 50 is considerably narrower than the cross-section of the suction pipe 20 and of the pressure pipe 24, so as to keep any loss of delivery liquid or pressure head of the pump as small as possible. If desired, in order to accelerate the suction, the suction pipe 20 may communicate with the upper part of the vessel 18 through a narrow passage, for example, in the form of a bore 56 in the suction pipe.

The level of the liquid in the supplementary vessel 18, when the pump is out of operation, is indicated at 52 in the suction pipe and pressure pipe. The supplementary vessel is then completely filled with liquid. When the pump is put into operation, the pump rotor 30 sucks liquid from the supplementary vessel 18 through a bottom opening 33 in the pump housing 32, and delivers the liquid into the pressure pipe 24. In this Way reduced pressure is produced in the upper part of the supplementary vessel 18 and this causes liquid to be sucked out of the container 10 through the suction pipe 20. The capacity of the supplementary vessel 18 must be sufiiciently large to ensure that the rotor 30 remains filled with liquid until the level of the liquid sucked up out of the container has risen to the height of the elbow 43. At this moment the level of the liquid in the vessel 18 will have fallen approximately to the level 54. The liquid continues to flow through the suction pipe 20 and issues from the opening 44 of the suction pipe into the supplementary vessel 18. Thus, the liquid is introduced below the level 54 of the liquid, in the vessel 18. In this way the formation of foam or bubbles due to the entrainment of air is precluded, even in the case of a low boiling liquid. As shown in FIGURE 2, the opening 44 of the suction pipe 20 is close to the wall of the vessel 18. The opening or outlet 44 of the suction pipe 20 also faces in a direction away from the inlet 33 of the pump, which prevents adsorbed air from entering the said inlet.

As shown in FIGURE 2, the opening 44 of the suction pipe is advantageously located in the supplementary vessel 18 at a higher level than the suction opening 33 of the pump, in order to prevent the air which at first issues from the opening 44 on starting up passing into the suc tion opening of the pump 33 and initially interrupting the operation of the pump.

When the pump is stopped, the liquid present in the pressure pipe 24 runs back through that pipe and through the vessel 18 and the suction pipe 20 into the container 10, and this continues until the level of the liquid in the pressure pipe 24 reaches the level of the opening 56 of the conduit 50 in the pressure pipe. Air can then pass through the conduit 50 into the suction pipe 20 and no further drawing off of liquid from the supplementary vessel 18 takes place. Thus, in this inoperative state, the liquid in the vessel 18 is at the level 52.

It will be understood that the invention is not limited to the embodiment shown in the drawings. Thus, the construction of the pump may be modified to suit particular operating-conditions. It is essential, however, that the suction pipe should have an elbow bend and terminate close to the bottom of the supplementary vessel, that is to say, below the level of the liquid during operation, and that it should communicate at its highest point with the pressure pipe by means of a narrow passage.

What is claimed is:

1. Apparatus for pumping a liquid from a container comprising a supplementary vessel disposed within the upper portion of the said container above the liquid level of'said container and a centrifugal pump and a casing therefor; said pump and casing being disposed within the supplementary vessel and provided with an impeller; said impeller being below the liquid level of said supplementary vessel, said supplementary vessel including a suction pipe with a U bend disposed above the top of the supplementary vessel and attached to the upper portion of the latter, said suction pipe having one arm extending downward into the lower portion of the container, and the other arm'extending downward into the lower portion of the supplementary Vessel but at a level higher than that of the inlet of the centrifugal pump, the outlet of said arm facing in a direction away from said inlet of said centrifugal pump whereby adsorbed air is prevented from entering the inlet of said pump; said centrifugal pump including a suction side for intake of liquid which communicates with the lower portion of the supplementary vessel and a pressure pipe extending upwards from the casing of the centrifugal pump; and a tube extending above the top of the supplementary vessel connecting said pressure pipe with said suction pipe at the U bend of the latter.

2. Apparatus for pumping a liquid from a container comprising a supplementary vessel disposed within the upper portion of the said container above the liquid level of said container and a centrifugal pump and a casing therefor; said pump and easing being disposed within the supplementary vessel and provided with an impeller; said impeller being below the liquid level of said supplementary vessel, said supplementary vessel including a suction pipe with a U bend disposed above the top of the supplementary vessel and attached to the upper portion of the latter, said suction pipe having one arm extending downward into the lower portion of the container, and the other arm extending downward into the lower portion of the supplementary vessel but at a level higher than that of the inlet of the centrifugal pump, the plane of the outlet of said arm being vertically disposed and said outlet facing in a direction away from said inlet of said centrifugal pump whereby adsorbed air is prevented from entering the inlet of said pump; said centrifugal pump including a suction side for intake ofliquid which communicates with the lower portion of the supplementary vessel and a pressure pipe extending upwards from the casing of the centrifugal pump; and a tube extending above the top of the supple- -mentary vessel connecting said pressure pipe with said suction pipe at the U bend of the latter.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,528 Lewis Jan. 20, 1931 1,972,410 Siemen et al Sept. 4, 1934 2,059,288 Stratton Nov. 3, 1936 2,179,858 Murphy Nov. 14, 1939 2,545,915 Bovee et al Mar. 20, 1951 FOREIGN PATENTS 740,815 Great Britain Nov. 23, 1955 831,903 Great Britain Apr. 6, 1960 

1. APPARATUS FOR PUMPING A LIQUID FROM A CONTAINER COMPRISING A SUPPLEMENTARY VESSEL DISPOSED WITHIN THE UPPER PORTION OF THE SAID CONTAINER ABOVE THE LIQUID LEVEL OF SAID CONTAINER AND A CENTRIFUGAL PUMP AND A CASING THEREFOR; SAID PUMP AND CASING BEING DISPOSED WITHIN THE SUPPLEMENTARY VESSEL AND PROVIDED WITH AN IMPELLER; SAID IMPELLER BEING BELOW THE LIQUID LEVEL OF SAID SUPPLEMENTARY VESSEL, SAID SUPPLEMENTARY VESSEL INCLUDING A SUCTION PIPE WITH A U BEND DISPOSED ABOVE THE TOP OF THE SUPPLEMENTARY VESSEL AND ATTACHED TO THE UPPER PORTION OF THE LATTER, SAID SUCTION PIPE HAVING ONE ARM EXTENDING DOWNWARD INTO THE LOWER PORTION OF THE CONTAINER, AND THE OTHER ARM EXTENDING DOWNWARD INTO THE LOWER PORTION OF THE SUPPLEMENTARY VESSEL BUT AT A LEVEL HIGHER THAN THAT OF THE INLET OF THE CENTRIFUGAL PUMP, THE OUTLET OF SAID ARM FACING IN A DIRECTION AWAY FROM SAID INLET OF SAID CENTRIFUGAL PUMP WHEREBY ABSORBED AIR IS PREVENTED FROM ENTERING THE INLET OF SAID PUMP; SAID CENTRIFUGAL PUMP INCLUDING A SUCTION SIDE FOR INTAKE OF LIQUID WHICH COMMUNICATES WITH THE LOWER PORTION OF THE SUPPLEMENTARY VESSEL AND A PRESSURE PIPE EXTENDING UPWARDS FROM THE CASING OF THE CENTRIFUGAL PUMP; AND A TUBE EXTENDING ABOVE THE TOP OF THE SUPPLEMENTARY VESSEL CONNECTING SAID PRESSURE PIPE WITH SAID SUCTION PIPE AT THE U BEND OF THE LATTER. 